[unreadable] The overall aim of this work is to investigate the neurobiological basis of behavioral sensitization to amphetamine in the context of individual differences. We aim to understand the interplay between psychosocial stress and the development of behavioral sensitization to amphetamine in the context of individual differences. Behavioral sensitization is relevant to drug addiction as it is thought that the neurobiological changes that may underlie sensitization to psychostimulants may be the same, or at least overlap with, changes that may cause addiction to drugs of abuse. Furthermore, it is thought that stress and glucocorticoids in particular, may mediate some aspects of behavioral sensitization as well as drug taking behaviors. We will examine how gene and protein changes in the dopamine and stress circuitry may mediate the propensity of some individuals to become sensitized to psychostimulants. We will use this model of individual differences to help understand how and why some individuals are more prone to the effects of drugs of abuse. [unreadable] [unreadable] [unreadable] [unreadable] [unreadable]